diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index a56a3eb..537c6e0 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -21,7 +21,7 @@ So examples should:
 complex logic that's extraneous to the WebExtension technology itself
 * demonstrate good-practice use of the technology, even at the expense of extra
 complexity
-* include useful optional manifest.json keys: `description` and `homepage_url`
+* include useful optional manifest.json keys: `description`, `icons`, and `homepage_url`
 
 Finally, note that the examples are all made available under the
 [Mozilla Public License 2.0](https://github.com/mdn/webextensions-examples/blob/master/LICENSE),